The invention relates generally to wireless communication technology, and more particularly to wireless communication systems having wireless wide area network (WWAN) and wireless local area network (WLAN) interfaces.
FIG. 1 illustrates typical service areas in which mobile terminals such as mobile phones are used. In these areas, the WWAN service area (e.g., GSM, GPRS, CDMA, 3G) may or may not overlap with a WLAN service area (as shown in FIG. 1). In the case where there is an overlap between the WWAN and WLAN service areas, both the WWAN and WLAN services are available. These overlapping areas are also referred to as hotspots, which include airports and hotels.
In hotspots (e.g., airports and hotels), people normally use mobile terminals for making voice calls and using low-speed data services via the WWAN and for using high-speed data services via the WLAN through an access point (AP). In situations in which two mobile terminals in the same hotspot or in different hotspots run by the same service provider are trying to communicate with each other, they still need to use the WWAN service to make voice calls. This is not cost effective even though a low cost alternative communication network, i.e., the WLAN, is available to both parties.
Therefore, there is a need to provide a cost effective method and system for seamlessly roaming between a WWAN and a WLAN in areas in which both services are available.